Download Operating Instructions ST 20

MAICO Diagnostic GmbH
Operating Instructions
MAICO ST 20
MAICO Diagnostic GmbH, Salzufer 13/14, D 10587 BERLIN, Tel. +49 30-70714650, Fax +49 30-70714699
Operating Instructions ST 20
Table of Contents
Page
1 Introduction............................................................................................... 3 2 Description ................................................................................................ 4 3 Getting started .......................................................................................... 6 4.1 Air Conduction (AC) test ......................................................................... 8 4.1.1 Screening test .................................................................................. 8 4.1.2 Hearing Threshold Test ..................................................................... 9 4.1.3 Masking in the air conduction measurement ...................................10 4.2 Test of the Bone Conduction (BC) (ST 20 BC and ST 20 SISI only) ...........11 4.2.1 Hearing threshold test .....................................................................11 4.2.2 Masking in the bone conduction measurement (ST 20 BC and ST 20
SISI)..........................................................................................................11 4.3 Tests in Free field (FF) with loudspeaker (optional) ..................................12 4.3.1 Reflex and Direction Tests for free-field measurements ....................12 4.4 How to run the SISI-Test (ST 20 SISI only) ...............................................13 4.4.1 Preparation of the Test ....................................................................13 4.4.2 Training of the Patient .....................................................................13 5 Recommended literature ...........................................................................15 6 Care and maintenance of the instrument ..................................................16 7 Trouble shooting ......................................................................................17 8 Individual Setup of the ST 20 ....................................................................18 9 Technical Data and Accessory ...................................................................20 10 Warranty, Maintenance and After-Sales Service ......................................24 11 Safety Regulations ..................................................................................25 11.1 Electrical Safety: ...................................................................................25 Geba_ST20_Fe_10a.doc
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11.2 Measuring security: ..............................................................................25 11.3 Device control:.....................................................................................25 11.4 Operation: ...........................................................................................25 11.5 Patient Safety: .....................................................................................25 Geba_ST20_Fe_10a.doc
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Operating Instructions ST 20
1 Introduction
Thank you very much for purchasing a quality product from the MAICO
family. This ST 20 audiometer is manufactured to meet all quality and safety
requirements, and has been certified with the CE-symbol according to
Medical Directive 93/42/EEC.
In designing the ST 20 we placed particular importance in making it a userfriendly device, meaning its operation is simple and easy to understand.
And because ST 20 functions are software controlled, upgrading later to new,
extended measurement functions will be simple and inexpensive. That means
that you have invested in a device that will adjust to your future needs.
This user manual should make it as easy as possible for you to become
familiar with the functions of the ST 20. Please open out the flap of
illustrations on the last page. The description of the position (e.g. ➄) of
controls, displays and connections, found again in the text, will make it easier
for you to learn how to operate the ST 20.
If you have problems or have ideas for further improvements, please get in
touch with us. Simply call.
Your MAICO-team
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2 Description
The audiometer ST 20 is a quick-testing screening audiometer for
audiometric tone examination of babies, children and adults. It is a handy
semi-automatic audiometer that is easy to operate, facilitates quick,
uncomplicated detection of hearing defects.
It has been designed for use in the office of the paediatrician and in general
practice, in the public health services and in occupational medicine.
As a result of modern microprocessor technology, the ST 20 is very
comfortable to use and has a high operating reliability. A PC interface for
data transfer to a connected computer is available (special interface cord
required).
The tests can be performed with a continuous or pulsed tone via
headphones. Masking with the opposite headphone is possible if needed. In
addition bone conduction measurement can be done with the ST 20 BC and
ST 20 SISI.
Free-field transmission is possible via the optional loudspeaker.
Moreover, the ST 20 SISI offers the opportunity to conduct the SISI-test.
The frequency and intensity level are set without any electronic static noises.
The test tone is adjusted by means of a slider control for the level (in 5 dB
steps) and the frequency adjustments are made by electronic push buttons.
The particular value of frequency/level is indicated by a red light point in the
audiogram field. In addition, the optional LCD-display (picture 2) shows level
and frequency (standard accessory of ST 20 SISI).
The ST 20 offers eight test frequencies from 250 Hz up to 8 kHz and a range
of -10 dBHL up to 100 dBHL for air conduction.
Picture 1 Front panel of ST 20The bone conduction measurement with the
ST 20 BC can be carried out with seven test frequencies from 250 Hz to 6
kHz and a range of -10 dBHL up to 70 dBHL.
If requested, the test signal can automatic be masked with the opposite
headphone.
The optional loudspeaker delivers
test levels from -10dBHL to 90
dBHL for free field measurement
at a distance of 10 cm.
Picture 1 Front panel of ST 20
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In addition to the features found in the ST 20
BC, the
ST 20 SISI offers the SISI-Test
diagnostic function.
For this purpose the ST 20 SISI is equipped
with a patient response switch and a LCDdisplay which shows level and frequency or the
SISI test information and the test score.
Picture 2 LCD- Display The patient response
switch is a standard accessory of the ST 20 SISI
but is offered as an option on the other Picture 2 LCD-Display
models.
Whenever the patient hears the test tone he
presses the patient response switch. The patient
response is indicated by the flashing of the red
light point. The audiometric value can easily be
marked on the audiogram paper.
Picture 3 Patient response switchWhen you
push any key of the ST 20, a message
(Flashtext) will be shown for a short time on
the optional LCD-Display (i.e. Masking on). This
message gives information about the function
or status of the key. This feature makes it easy
for inexperienced users to get familiar with the
ST 20.
The audiometer is designed to be extremely
service friendly. Automatic test programs make Picture 3 Patient response switch
trouble shooting and the yearly check as easy as possible.
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3 Getting started
The ST 20 should be operated in a quiet room, so that the audiometric
examinations are not influenced by outside noises. However, the sound
insulation muffs of the headphones perform so well at excluding sound the
instrument can be used in noisier environments.
Electro-medical instruments, which emit strong electromagnetic fields (e.g.
microwaves - radiotherapy devices), can influence the function of the
audiometer. Therefore the use of these instruments is not allowed in close
proximity to the audiometer.
The test room must be at normal temperature, usually 15° C to 35° C, and
the instrument should be switched on about 10 minutes before the first
measurement to guarantee precise measuring results. If the device has been
cooled down (e.g. during transport), please wait until it has warmed up to
room temperature.
Insert the instrument plug of the mains cord into the mains socket on the rear
of the instrument ±. Insert the other end of the mains cord into a 230
V~shock-proof socket.
Connect the right (red) headphone
to the correspondingly labelled socket
¯ and the left (Blue) headphone to socket ° at the rear of the device. If your
device is equipped with a patient response switch, plug it to socket ¬♦.
The LCD-display is connected to socket «♣ and screwed into the ST 20.
The bone conduction receiver of ST 20 BC and ST 20 SISI is connected to
socket ®♠.
The optional loudspeaker is connected to socket ­♥.
Picture 4 rear panel of ST 20 with connectors
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Slide the level control Ë completely to the top and turn on
the device with switch Ã. The device starts its initial test
automatically. During this test, all the light points (LED́s) Î
in the audiogram form Í light up. After the test the 1 kHz
light point Î in the audiogram form Í and the green signal
presentation LED ♪ Ì light up (only in interrupter mode).
It in dicates that the test tone can be heard. If the green
signal presentation LED ♪ Ì does not light up and the 1
kHz light point Î flashes, the level control Ë needs to be
set at -10 dB.
Due to the built-in protective device the test signal has
been faded out automatically.
Picture 5 mains switch,
slider level control
Patient safety:
The built-in protective device makes sure that during the initialization or when
changing the channel as well as from air conduction to bone conduction or
free field the patient’s ear is protected from high sound exposure. The
protective device is triggered by sound levels more than 50 dBHL, and fades
out the test sound. This is indicated by the flashing of the light points Î in the
audiogram form Í and green signal presentation LED♪ Ì In this case, set the
level control Ë to the upper position and when the light point stops flashing,
the green signal presentation LED Ì lights up and the test sound is faded in.
If during the initialization of the device the 250 Hz and 500 Hz light points Î
start to flash, the device has detected an error. In this case, contact customer
service (see chapter 10).
Calibration of the device:
The instrument, headphones, bone conduction receiver (ST 20 BC and ST 20
SISI only) as well as the optional loudspeaker match one another and have the
same serial number (e.g. 6631520). It is not allowed to use the device with
other transducers. If one of the acoustic transducers is replaced, the
instrument must be recalibrated.
The use of non-calibrated
measurements!
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Operating Instructions ST 20
4 Test procedure
4.1 Air Conduction (AC) test
4.1.1 Screening test
-
-
The patient should sit at a distance of at least
1 m from the device.
Before putting on the headphones set the
slider level control Ë at -10 dB.
Eliminate any obstructions which will interfere
with the placement of the earphone cushions
on the ear (i.e. hair, eyeglasses).
Ensure the headphones are put on correctly.
Red side on the right, blue side on the left.
Adjust the headband of the headphones so Picture 6 Headphone
that the receivers are at the correct height (the
sound output grid Ò exactly facing the ear channel).
Place the audiogram paper on the two holding pins.
Press the key Ä until the according LED lights (for AC).
Press the red key È for the right ear or
the blue key É for the left ear.
Controls and displays
à Power switch
Ä AC - BC
- FF
Å Masking
Æ Pulse
Ç SISI
È Right ear (red)
É Left ear (blue)
Ê Signal-interrupter key
Ë Level slide control
Ì Signal presentation ♪
Í Audiogram form
Î Light point
Ï Frequency down
Ð Frequency up
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Picture 7 Front panel of ST 20 with controls and displays
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- Set the slider level control Ë at 30 dB.
- Test through the frequencies.
(After switching on, the frequency is automatically set to 1 kHz.)
Start at 1 kHz, set the higher frequencies first then the low
frequencies.
- Use the right key
Ð to select the higher frequencies and use the left key
Ï to select the lower frequencies.
Use the interrupter key Ê to interrupt the test tone. The green signal
presentation LEDÌ should extinguish.
- If the patient hears the test tone, the particular value is displayed by a light
point Î in the audiogram field Í and should be marked on the audiogram
paper.
The correct markings are: O (red) = right and X (blue) = left
If all tones are heard it can be assumed that the hearing loss, if any, is only
minimal.
For hygienic reasons it is important to clean the ear cushions of the
headphone (see chapter 6).
4.1.2 Hearing Threshold Test
In the hearing threshold test, the hearing threshold of the patient is measured
in comparison with the normal hearing threshold for air conduction. The test
is started on the ear with better hearing.
- Set the slider level control Ë
to -10 dB
- Using the key È or É, choose
the ear that hears better.
- Use the key Ï, Ð to set the
test frequency at 1 kHz.
- For further preparation, see
4.1.1 (screening test)
- Instruction to the person
being tested:
Whenever the test tone is just
audible, the patient should
raise their hand or
press the patient response
Picture 8 Controls of ST 20
switch.
- Increase the test level with
the slider level control Ë gradually, until the
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patient indicates that he/she can just hear the test tone.
- Press the interrupter key Ê and mark the light point Î on the audiogram
form Í .
- Set the slider level control Ë back to -10 dB, select the next frequency,
increase the level again. Test through the other frequencies in the same way.
- Choose with key È or É the poorer ear and repeat the hearing threshold
test.
4.1.3 Masking in the air conduction measurement
In the air conduction threshold measurement, the opposite ear must be
masked if a larger difference between both ears appears. The masking signal
is a broad band noise which will be selected automatically 15 dB lower than
the actual hearing level setting. The masking signal is applied to the opposite
ear through the air conduction headset. Opposite ear
describes the current not tested ear (if the left ear is
tested - the right ear is the opposite ear). This Picture 9 LCD-display
masking signal masks the test tone and prevents a Masking on
detection of the test signal through the "better" ear.
- Press key Å to enable the masking. If your ST
20 has the optional LCD-display, for a short
Picture 10 LCD-display
time a corresponding message is displayed (see Test- and masking level
picture 9). Later the actual test level is
displayed on the left and the masking level on
the right of the LCD-display. Example picture
10 shows a test level of 50 dBHL and a Picture 11 LCD-display
Masking off
masking level of 35 dBHL.
- To disable masking press key Å again. If your ST 20 has the optional
LCD-display, for a short time a corresponding message is displayed (see
picture 11).
Attention!
When the channel (R/L) is changed or the acoustic transducer (AC
or BC
or FF ) is changed, the frequency is automatically set to the starting point of
1 kHz. This function can be turned off in the setup menu (see chapter 8).
If the acoustic transducers or the channel (R/L) cannot be selected, set the
level control Ë to -10 dB.
If the maximum permitted level for the headphones, bone conduction receiver
or loudspeaker is exceeded, the test signal will not increase. The
corresponding light point Î in the audiogram form Í flashes to indicate that
the level limit has been reached.
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4.2 Test of the Bone Conduction (BC) (ST 20 BC and ST 20 SISI only)
4.2.1 Hearing threshold test
In the hearing threshold test, the hearing
threshold of the patient is measured in
comparison with the normal hearing threshold
for bone conduction.
Differences in the measured hearing threshold
for air conduction (see 4.1.2) give indications
Picture 12 Bone conductor
of problems in the middle ear.
- Set the slider level control Ë to -10 dB.
- Place the bone conduction receiver so that the flat, circular side of the
transducer Y is placed on the mastoid, at the noticeable ledge of the cranial
bone behind the auricle. The other side of the headband is placed in front of
the opposite ear.
- Select BC by pressing key Ä until the lamp under the
symbol lights.
- Perform the test the same way as for air conduction (see 4.1.2). Enter the
measurements for all frequencies on the form, connect all points with dotted
lines marked on the audiogram form as follows: > = right and < = left.
4.2.2 Masking in the bone conduction measurement (ST 20 BC and ST
20 SISI)
In the bone conduction threshold measurement, the opposite ear must be
masked if a difference of at least 10 dBHL between both ears appears. The
masking signal is a broad band noise which will be selected automatically 15
dB higher than the actual hearing level setting. The masking signal is applied
to the opposite ear through the air conduction headset. Opposite ear
describes the current not tested ear (if the left ear is tested - the right ear is
the opposite ear). This masking signal masks the test tone and prevents a
detection of the test signal through the non tested ear.
- Press key Å to enable the masking. If
your ST 20 has the optional LCD-display,
for a short time a corresponding
message is displayed (see picture 13).
Later the actual test level is displayed on
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Picture 13 LCD-Display
Masking on
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Operating Instructions ST 20
the left and the masking level on the right of the LCD-display. Example
picture 14 shows a test level of 50 dBHL and a masking level of 65
dBHL.
- To disable masking press key Å again. If your
ST 20 has the optional LCD-display, for a short
time a corresponding message is displayed (see
picture 15).
Picture 14 LCD-Display
- Continue as described before under 4.2.1 Test- and masking level
bone conduction test.
- Put the headphone with the according side
on the opposite ear, with the other side on the
cheek bone in front of the test ear. Adjust the Picture 15 LCD-Display
headband so that the headphone sits at the Masking off
right height to the opposite ear (the sound
grid Ò exactly facing the auditory passage(see chapter 4.11)).
The marking for bone conduction with masking should be done with the
symbols [on the right and] on the left in the audiogram form.
For hygienic reasons it is important to clean the bone conduction receiver (see
chapter 6).
4.3 Tests in Free field (FF) with loudspeaker (optional)
4.3.1 Reflex and Direction Tests for free-field measurements
The test with babies and infants is performed with pulsed
tones.
- Set the level control Ë at -10 dB.
- Select FF by pressing key Ä until the lamp under the
symbol lights.
- Press the pulse key Æ
- The sound is switched on and off periodically.
- The green signal presentation LED ♪ Ì flashes.
- When it lights up the test tone can be heard.
Picture 16 Loudspeaker
- Position the loudspeaker about 10 cm away from the ear
to be tested.
- Present the test tone by pressing the switch at the rear of the loudspeaker.
- Increase the level control Ë slowly.
- When the child shows a reaction (e.g. turns the head) enter the
measurement on the audiogram form with the remark “loudspeaker testing”.
- Use the frequency keys
/
Ï, Ð to select higher or lower
frequencies.
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4.4 How to run the SISI-Test (ST 20 SISI only)
The SISI (Short Increment Sensitivity Index) - test provides a measurement in
the supraliminal intensity area. It offers additional information to the hearing
thresholds measured in sections 4.1.2 and/or 4.2.1. Thereby it is possible to
distinguish between sensory (inner ear) and neural (auditory nerve) hearing
damage.
The SISI-test is started by pressing the SISI key Ç.
To train the patient to the SISI-test, louder
increments of 5, 2 and 1 dB are presented to the
patient before the test. The test tone is increased
by 1 dB for a period of 0.2 seconds every 4.8
seconds.
Whenever the patient hears the increment, he/she Picture 17 SISI_Display
presses the patient response switch. The SISI-test
information and the test score are shown on the LCD-display. The test will
end automatically after 20 presented increments.
4.4.1 Preparation of the Test
- Set the test frequency with the frequency keys Ï or Ð. For the test you
should choose the frequency level where the maximum bone conduction
hearing loss was measured (see 4.2.).
- Set the test level with the level control slider Ë. The volume is set to 20 dB
above the individual hearing threshold (measured under section 4.2). It must
reach at least 60 dBspl.
- The patient must be instructed: "You will now hear a continuous tone. Every
time it becomes louder, immediately push the key”.
4.4.2 Training of the Patient
Only with careful training during the following
conditioning phase can a valid test result can be
Picture 18 start display
achieved.
- The SISI-test is started by pressing the SISI key
Ç.
- The LCD-display indicates for approx. two
seconds the text shown in picture 18.
Picture 19 cond. 5 dB
- Then the following text is shown on the LCD
display, see picture 19. The left figure indicates the current modulation level.
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Operating Instructions ST 20
Initially the value is 5 dB. That means the patient is presented with a
continuous tone which is briefly increased every 4.8 seconds, e.g. 60 dBHL to
65 dBHL. This effect is shown on the LCD display by a note. The white small
box appears for approx. 1,5 seconds. During this period the patient may
respond. If he/she answers too early or too late the answer will not be
accepted by the ST 20.
- When the patient presses the response switch
the examiner will see a black box on the display
Picture 20 patient answer
(see picture 20).
- The number of detected increments is counted
and shown on the display. Furthermore, the
number of presented increments is shown, s. Picture 21 valid answer
picture 21.
- When you are sure that the patient has
understood the object of the test, press the SISI
key Ç again. The modulation level will be reduced Picture 22 cond. 3 dB
to 3 dB.
- If the patient has understood this part of the test
also, press the SISI keyÇ. The modulation level will
be reduced to 2 dB.
Picture 23 cond. 2 dB
- If the patient has understood the test up to here,
press the SISI key Ç again to begin the SISI test.
The LCD-display indicates SISI (see picture 24) and
the modulation level is adjusted to 1 dB. Now 20
increments will be presented to the patient and Picture 24 start SISI-Test
the examiner can follow the test on the LCD
display (see example picture 25).
- The test will end automatically after 20
presented increments. The number of detected Picture 25 Example SISI-Test
increments is counted and indicated as a
percentage (see picture 26). The percent result
and the test frequency are entered in the middle
of the audiogram form.
- If you are sure that the result of the test is stable Picture 26 result SISI-test
you can interrupt the test at any time by pressing
the pulse key Æ. The result is then indicated
accordingly (picture 27).
- Retrocochlear (neural) hearing damage is Picture 27 result SISI-test
represented by results < 25 %, a cochlear (inner with manual stop
ear) defect by values > 70 %.
- Press the SISI key Ç to leave the SISI-test.
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5 Recommended literature
Audiometric Interpretation:
A Manual of Basic Audiometry
Lloyd, Lyle L., and Harriet Kaplan
Baltimore: University Park Press, 1980
Auditory Disorders:
A Manual for Clinical Evaluation
Jerger, Susan, and James Jerger
Boston: College Hill Press, 1981
Handbook of Clinical Audiology
Katz, Jack
Baltimore: William & Wilkins, 1994
Roeseŕs Audiology Desk Reference
Roeser, Ross J.
New York / Stuttgart: Thieme, 1996
Auditory Diagnosis
Silam, Shlomo and Carol A. Silvermann
San Diego / London: Singular Publishing Group,
1997
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6 Care and maintenance of the instrument
Disconnect the mains plug before cleaning!
- To clean the instrument, headphones, bone
conduction
receiver
and
loudspeaker use a soft cloth dampened with a little
warm soapy water or washing-up liquid; no alcohol
or spirits should be used.
- The headphone cushion and the ear cushions of
the headphone Holmco 8103 can be detached for
cleaning. Please proceed as shown in picture 28. To
remove the ear cushion first remove the rubber
ring. To assemble the cleaned or changed ear
cushion start at the rounded location of the
headphone.
- During cleaning, please ensure that no liquid runs
into the switches, level control, headphone
capsules or loudspeaker openings.
Picture 28 changing of the ear
cushions of Holmco 8103
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7 Trouble shooting
If you should find that your instrument is no longer working properly during a
test run, please check the following points:
The acoustic transducers cannot be selected:
- Level control Ë must be set at -10 dB and the required key pressed.
Diodes do not light up and there is no light point Î on the audiogram
field Í:
- Is the mains lead plugged in correctly?
- Is the power switch à at the “On” (|) position?
Light point available, but test tone is absent:
- Green signal presentation LED Ì does not light:
- Level control Ë must be set at -10 dB position.
- Press signal-interrupter key Ê. (When the LED Ì lights up and the tone is
available, the device works in presenter mode). For switching over to
interrupter operation press the SISI key Ç longer than 3 seconds.
- Are the acoustic transducers connected to the correct socket?
- Is key Ä in the right position?
- Is the lead connecting the headphones or the loudspeaker loose or
defective?
If your instrument still does not work properly after this short check, please
consult your dealer or send the instrument to your dealer or our service centre
(see also chapter 10).
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8 Individual Setup of the ST 20
Only with optional LCD-Display or ST 20 SISI possible.
The ST 20 is configured to meet most requirements. But it is also possible to
setup some functions of the ST 20 to your individual needs. These changes
will be stored in the ST 20, even after you switch it off, until you change it
again in the setup.
- To get into the setup-menu of the ST 20 press the red key È and switch on
the instrument with the power switch Ã.
- Keep the red key È pressed until you see on the LCD-Display the text “ST 20
II”.
- After releasing the red key È the message “User
menu” and then the text shown in picture 29
appears on the LCD-Display.
Picture 29 Setup
- You can toggle between the different items of Continuous pulse
the setup menu using the frequency keys Ï and
Ð.
- Select a particular item by pressing the signal-interrupter key Ê.
- You see the actual setting flashing on the left of the LCD-Display.
- Change the actual setting with the frequency keys Ï and Ð.
- Save the new setting with the signal-interrupter key Ê.
- Toggle through further items of the setup-menu with the frequency keys Ï
and Ð.
- Leave the setup-menu by pressing the pulse key Æ.
The setup-menu of the ST 20 offers the following choices:
The test signal is a steady tone
The test signal is a pulse tone
Pressing the signal key Ê interrupts the test
signal
Pressing the signal key Ê presents the test signal
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Operating Instructions ST 20
The Flashtext time (Function description of
pressed key on the LCD-Display) is long (app.
seconds). Setting for inexperienced users.
The Flashtext time (Function description of
pressed key on the LCD-Display) is short (app.
seconds). Setting for experienced users.
a
3
a
1
Pressing the frequency key Ï or Ð at the lowest
(250 Hz) or highest (8 kHz) resets the frequency
to 1 kHz.
Pressing the frequency key Ï or Ð at the lowest
(250 Hz) or highest (8 kHz) frequency“rolls” the
frequency over to the highest (8 kHz) or lowest
(250 Hz) frequency.
Changing between AC, BC or FF with key Ä
keeps the actual test frequency unchanged.
Changing between AC, BC or FF with key Ä
resets the test frequency to 1 kHz.
Choose your language for the text on the LCDDisplay. Possible selections are English, French,
Spanish and German.
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9 Technical Data and Accessory
The ST 20 audiometer is an active, diagnostic medical
product according to the class IIa of the EU medical
directive 93/42/EEC.
Audiometer Class: A 4 according to EN 60 645-1
Test-Frequency: 250 Hz, 500 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz, 8 kHz
Sound Pressure Level: 5 dB level steps
AC with earphone Holmco type 8103 B 26:
- 10 dBHL ... 100 dBHL(for 250 Hz, 6 kHz, 8 kHz to
90 dB)
BC with bone conduction receiver B-71
(only ST 20 BC, SISI):
- 10 dBHL ... 70 dBHL(for 250 Hz ... 35 dB, 6 kHz ...
40 dB; 500 Hz, 4 kHz ... 60 dB; 3 kHz ... 65 dB)
FF with loudspeaker (optional):
- 10 dBSPL... 90 dBSPL (measurement 10 cm away
from the ear)
Test Signal:
Pure tone or pulse tone
Masking Signal:
broadband (white) noise
Masking Level:
automatic:
AC: 15 dB lower as the actual test level
BC: 15 dB higher as the actual test level
Modulation:
pulse tone: on/off modulation time 0,5 s
SISI-test: 5 dB, 3 dB, 2 dB conditioning
1 dB test
Modulation time 4,8/0,2 s
Interrupter:
Interruption or presentation of the test signal
(changeable via setup-menu)
Power Supply:
230 V / 50 Hz ±10 %
Power Consumption: 4 VA
Device Fuses:
50 mA semi time-lag (internal)
Warm up time:
> 10 min after power on
Environment conditions: + 15 ... + 35 ̊C (operation)
+ 5 ... + 50 ̊C (storage)
Maximum humidity 90 % (storage and operation)
Dimensions:
W x H x D: 29 x 22 x 6 cm
Weight:
1,9 kg
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Operating Instructions ST 20
Connectors:
Connection
Specification
« serial PC-Interface
RS 232 C
¬ Patient response switch sleeve=ground, tip=input
RI= 100 kS
­ Loudspeaker
sleeve=ground, tip=output ZO= 8S,UO= 3,5 VRMS
® Bone conductor (BC) sleeve=ground, tip=output ZO= 8S,UO= 3,5 VRMS
¯ Headphone (AC) right (red) sleeve=ground,tip=output ZO=8S,UO=3,5 VRMS
° Headphone (AC) left (blue) sleeve=ground, tip=output ZO=8S,UO=3,5 VRMS
± Mains socket
left/right=mains
230 V~, 50 Hz
Picture 30 rear of ST 20 with connection plugs
Calibration values: AC-Receiver Holmberg 8103 B 26
Reference
equivalent
sound pressure level
according to ISO 389 - 1
Force: 13 ... 16 N
threshold
with Coupler according to IEC
303
Frequency [Hz]
[dB] (re 20 :Pa)
sound damping [dB]
250
25
14.5
500
18.5
18.5
1000
12
25
2000
9.5
36.5
3000
9
41
4000
9
44
6000
19.5
-
8000
20
35
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Operating Instructions ST 20
Calibration values:
Frequency [Hz]
250
500
1000
2000
3000
4000
6000
Calibration values:
Frequency [Hz]
250
500
1000
2000
3000
4000
6000
8000
Geba_ST20_Fe_10a.doc
BC-Receiver Radioear B-71
Reference
equivalent
threshold force level
according to ISO 389-3
[dB] (re 1 :N)
67
58
42.5
31
30
35.5
40
Force: 4,9... 5,9 N
air radiation
HTLAB - HTLB
minimum / maximum
[dB]
4/1 8
10,5/ 31
FF-Loudspeaker (Part. No. 801503)
Reference sound pressure level
[dB] (re 20 :P)
-2.5
0
0
-1
0
0
-1
0
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Operating Instructions ST 20
Standard accessories:
1 air conduction receiver Holmco 8103 B 26
1 pad of audiogram paper (50 sheets)
1 mains cord
1 bone conduction receiver B 71
(ST 20 BC, ST 20 SISI only)
1 patient response switch (ST 20-SISI only)
1 LCD-display (ST 20 SISI only)
Optional accessories:
Carrying case for the device and accessories
Part. No. 705050
Loudspeaker
Part. No. 801503
Headphone padding for children
Part No. 8698847632
Patient response switch
Part No. 80101249
LCD-display for level and frequency
Part No. 80 20 90
Consumables:
5 pads of audiogram paper (50 sheets)
Part No. 861001
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Operating Instructions ST 20
10 Warranty, Maintenance and After-Sales Service
The MAICO ST 20 is guaranteed for 1 year.
This warranty is extended to the original purchaser of the instrument by
MAICO through the distributor from whom it was purchased and covers
defects in material and workmanship for a period of one year from date of
delivery of the instrument to the original purchaser.
The ST 20 may be repaired and serviced only by your dealer or by a service
center recommended by your dealer. We urgently advise you against
attempting to rectify any faults yourself or commissioning non-experts to do
so.
In the event of repair during the guarantee period, please enclose evidence of
purchase with the instrument.
In order to ensure that your instrument works properly, the ST 20 should be
checked and calibrated at least once a year. This check has to be carried out
by your dealer.
When returning the instrument for repairs it is essential to send the
headphones, as well. Send the device to your dealer or to a service center
authorized by your dealer. Please include a detailed description of faults. In
order to prevent damage in transit, please use the original packing if possible
when returning the instrument.
Within the European Union it is illegal to dispose electric and
electronic waste as unsorted municipal waste. According to
this, all MAICO products sold after August 13, 2005, are
marked with a crossed-out wheeled bin. Within the limits of
Article (9) of DIRECTIVE 2002/96/EC on waste electrical and
electronic equipment (WEEE), MAICO has changed their
sales policy. To avoid additional distribution costs we assign
the responsibility for the proper collection and treatment
according legal regulations to our customers.
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Operating Instructions ST 20
11 Safety Regulations
11.1 Electrical Safety:
The ST 20 audiometer is constructed to comply with protection
class II of the international standard IEC 601-1 (EN 60601-1).
Protection from an electric shock is ensured even without the
system earth connection. The instruments are not intended for
operation in areas with an explosion hazard.
11.2 Measuring security:
To guarantee that the audiometer works properly, the instrument has to be
checked and calibrated at least once a year.
The service and calibration must be performed by an authorized service
center. In accordance with the regulations of the EU medical directive we will
drop our liability if these checks are not done.
The use of non-calibrated audiometers is not allowed.
11.3 Device control:
The user of the instrument should perform a subjective instrument check
once a week. This check can be done following the list for subjective
instrument check (see next page). For your own security, you should copy the
enclosed list, fill it in once a week and store it in your files.
11.4 Operation:
Only skilled personnel (Audiologists, ENT professionals or other with
equivalent knowledge) should operate the instrument.
11.5 Patient Safety:
Please note that if connection is made to standard equipment like printers
and network, special precautions must be taken in order to maintain medical
safety. Connecting this device to other devices in order to make a system
may cause the safety specifications to be invalid. It is therefore recommended
to insert a galvanic separation between the device and the host computer,
unless the computer is battery operated or supplied by a medical approved
power supply. Galvanic separation must fulfil the EN 60 601-1.
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Operating Instructions ST 20
Checklist for Subjective Audiometer Testing
- Clean the ear and head cushion!
- Untangle all lines when necessary
- Are the headphone cushion in good condition?
If not Æ replace
- Are plugs and leads in good condition/ undamaged?
- Are all controls working properly?
- Is the Patient Response Key working properly (if available)?
- Check batteries and renew if necessary?
Instrument:........................................
Manufacturer:…................................
Serial No.:.........................................
Examiner:........................................
Test Signal Quality
All the test frequencies in the below table indicate typical hearing level and can be changed when necessary:
Masking: “B” for Buzz tone, “G” for Noise, “V” for signal distortion, “S” for switching masking noise.
Right Ear
kHz 0,25 0,5 1
Level
2
3
4
6
8
Left Ear
0,25 0,5 1
2
3
4
6
8
kHz
30dB HL
50dB HL
70dB HL
30dB HL
50dB HL
LL
KL
* When noise “B”, “G”, “V” or “S” is blocked, inform the service center!
* When the test tone is heard at the masking ear, contact the service center!
Air Conduction Audiogram
kHz
Right Ear
0,25 0,5 1
Level
2
3
4
6
8
Left Ear
0,25 0,5 1
2
3
4
6
8
kHz
Should
dBHV*
Is
dBHV
Is
dBHV
Left
Earpiec
Right
Earpiec
e**
Left
Earpiec
Right
Earpiec
e **
* Should is the last measurement of the patient
**For inverted measurement please reattach the headphone
If the frequency difference between „Should“ and „Is“ for one ear averages more than 10 dB, contact the SERVICE CENTER!
Bone Conduction Audiogram
Right Ear
kHz 0,25 0,5 1
Level
2
3
4
6
8
Left Ear
0,25 0,5 1
2
3
4
6
8
kHz
Should
dBHV*
Is
dBHV
If the frequency difference between „Should“ and „Is“ for one ear averages more than 10 dB, contact the SERVICE CENTER!
Tested.............................................................................................
Date:...............................................................................................
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Operating Instructions ST 20
Specifications are subject to change
MAICO Diagnostic GmbH
Salzufer 13/14
1058 Berlin
Telefon +49 30 - 70 71 46 50
Telefax +49 30 - 70 71 46 99
e-mail: [email protected]
Internet: www.maico.biz
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851 307/1 04/10
Front panel with controls and displays
à Power switch
Ä AC , BC
, FF
Å Masking key
Æ Pulse key
Ç SISI key
key
lighting LED shows if AC, BC or FF is selected
LED lights when masking is on
LED lights when pulse is on
LED lights when SISI test is selected (SISI function only
with ST 20 SISI) (Press more than 3 sec. to toggle
between Presentation or Interruption of the test tone)
LED lights when right (red) ear selected
È Right ear (red)
(to access Setup-menu press right ear key during
power-on (only with optional LCD-display or ST 20 SISI)
É Left ear (blue)
LED lights when left (blue) ear selected
Ê Signal-interrupter / presenter key (mode change with SISI key)
Ë Level slider
Ì Signal presentation
Í Audiogram form
Î Lightpoint
4 5
2 3
1
SISI
6 7
R
L
I
O
LED lights = test signal on
LED off = test signal off
LED flashes = test signal pulses
shows actual level and frequency
flashes when optional patient response switch is pressed
dB
Ï Frequency down œ
Ð Frequency up ›
Hz
MAICO ST 20
Rear panel with connectors
« Serial PC-Interface or optional LCD-Display
¬ Patient response switch
­ Loudspeaker
® Bone conductor (BC)
¯ Headphone (AC) right (red)
° Headphone (AC) left (blue)
± Mains socket (230 V~ 50 Hz)
12 13
8 9 10 11
MULTI-PORT
A
14
R
B
C
D
E
L
F
G